question_answer

In a single slit diffraction pattern, how does the angular width of central maximum change, when (i) slit width is decreased, (ii) distance between the slit and screen is increased and (iii) light of smaller visible wavelength is used? Justify your answer in each case.                    

Answer:

                Linear width of central maximum, \[{{\beta }_{0}}=\frac{2D\lambda }{d}\] Angular width of central maximum\[=\frac{{{\beta }_{0}}}{D}=\frac{2\lambda }{d}\] (i) When slit width d decreases, angular width increases,                         (ii) When distance D between the slit and screen is increased, angular width does not change. (iii) When light of smaller wavelength \[\lambda \]is used, angular width decreases.